Crystallographic orientation-dependent photo-response of planar cadmium telluride X-ray detectors

Cadmium telluride (CdTe) crystals are widely used for X-ray detection in applications ranging from medical imaging to non-destructive industrial inspection. The surface charge carrier dynamics and photo-response of the crystals are critical factors that determine their per8formance. Here, we reveal the influence of crystallographic orientation of CdTe crystals on their photo-induced behaviors. Notably, X-ray detector devices fabricated from the (110) lattice plane exhibit more than two-orders of magnitude lower X-ray detection limit and a substantially higher X-ray sensitivity over the devices fabricated from either (100) or (111) crystal planes when subjected to a bias of 0.1 V. These findings are elucidated through comprehensive investigations by time-resolved spectroscopic and four-dimensional electron microscopic experiments, further supported by high-level density functional theory calculations. This discovery highlights the pivotal role of selecting an appropriate crystallographic orientation in enhancing the detection performance of high-energy X-ray sensors, thereby benefiting various X-ray imaging applications.